One of the most common questions relating to identical twins is the issue of mirror imaging.

What is it?

‘Mirror image’ is a type of identical twinning. It can happen in any type of identical twins. When the split occurs late - more than a week after conception - the twins can develop reverse asymmetric features. This term is not really a type of twin, just a way to describe their physical features. Twins that split later than this can result in conjoined twins.


The major characteristics of mirror imaged twins are they usually have opposite features such as

  • hair whirls
  • left/right handedness
  • mirror twins can have the same eye conditions in opposite eyes
  • opposite teeth eruption
  • some mirror image twins cross their legs opposite to each other
  • in extreme cases, twins can even have reversed organs

Mirror imaging is never the same for every set of twins – it is a matter of degrees. Not every set of mirror twins is opposite handed and not every set has different hair whirls.


Many assume that mirror imaging is a separate type of twin. They’ll list “identical” ”non-identical” or “mirror image” when completing forms. However, mirror imaging is simply an example of identical twinning.

Identical twins do not have to be identical in every way –and can in fact exhibit more differences as they age.

Ascertaining if a twin is mirror-image or not cannot be determined via a DNA test – this will only confirm if they are identical or not; it can only be done by looking at the twins themselves. 

Twins Research Australia

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Twins Research Australia has received continuous funding from the National Health and Medical Research Council (NHMRC) since 1981, most recently through a Centre of Research Excellence Grant (2015-2022). TRA is administered by the University of Melbourne.

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